1. Field of the Invention
The present invention relates to a compiler for a computer language, and more particularly to a method for efficiently utilizing a hardware of the computer. Further more particularly, it relates to analysis of subscripts of an array in loop processing for utilizing a vector function of the computer and increasing a processing speed by reutilization of an operation result.
2. Description of Related Art
A compiler analyzes a source program and compiles it to an object program in an execution form by adding to the source program a process to improve a utilization efficiency in prosecution of the program (which is called an optimization process). In the prior art, the above process is carried out when a subscript (j) of an array (A(j)) described in a DO loop in the source program is represented by a single definition, but the above process cannot be carried out when two or more definitions are included. Such a process is described in Journal of Information Processing Society of Japan, Vol. 24, No. 2, pages 238-248 (1983).
However, in order to enhance the efficiency of the computer, it is necessary to carry out the optimization process when even two or more definitions are included.